<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
	</head>
	<body>
		<script type="text/javascript">
			
			try{
				document.forms.input.length
				console.log("代码结束");
			}catch(exception)
			{
				alert("出现异常，捕获处理")
			}finally
			{
				alert("始终要执行的代码")
			}
			
			alert("正常结束")
			
			
		</script>
	</body>
</html>